The present invention relates to a mechanism for cutting extra portions of staple legs which penetrate a material to be bound and protrude from the underside thereof.
Materials to be stapled have a variety of thicknesses, but staple leg length cannot as a practical matter be varied. Hence, the length of the staple legs must be set to the maximum thickness of the material to be stapled. Thus, if the staple legs are substantially longer than the thickness of the material, the staple legs often penetrate the material and further repenetrate it from the underside thereof even to such an extent that the legs are partly exposed from the surface thereof.
In order to prevent this, there has been proposed a stapler including a mechanism for cutting the extra portions of legs if the staple legs are too long. A well known stapler of this kind is disclosed in, e.g., Japanese Patent Laid-Open Publication No. 102301/1982. As illustrated in FIG. 4 of this Patent Laid-Open Publication, the unnecessary portions of the staple legs after penetrating the material are cut by movable cutting edges 71 and 72 and fixed cutting edges 73 and 74. At this time, the staple legs are clinched simultaneously when being cut because a movable clincher is formed with the movable cutting edges 70 and 71.
However, with such a movable clincher, accuracy must exist between the two movable cutting edges of the movable clincher which respectively make a circular motion and the one fixed cutting edge. This takes much labor to set the dimensions of parts, process the parts and assemble them. In addition, unfavorable conditions both in cutting and in the clinching are apt to be created, since the timing between movements of the two movable edges is critical.
This kind of stapler is further provided with means for processing the cut-scraps in order to prevent problems such as gear scuffing and damage to circuit substrates caused by short-circuits from scattered cut-scraps. One approach is to suck in the cut-scraps by air into a storage. It is not, however, economical to employ an effective power source such as air or the like for processing the cut-scraps.
These problems are overcome in the present invention in which legs are cut in a stapler which is capable of securely and sequentially driving the staple into the material, cutting the staple legs if the staple legs passing through the material exceed a predetermined length, and clinching.
According to another aspect of the invention, the cut-scraps of the staple legs are disposed of without making use of any special power source.
For the purpose of solving the above-mentioned problems, the stapler of the present invention includes a movable cutting member provided underneath a pair of movable clinchers, this movable cutting member being movable in a direction substantially orthogonal to the penetrating direction of the staple legs and including a staple receiving portion formed with first cutting edges engaging with the staple legs penetrating the material, and a fixed cutting member disposed in the forward direction of movement of the movable cutting member, this fixed cutting member having a second cutting edge for cutting the staple legs in cooperation with the first cutting edges of the movable cutting member and a guide portion for guiding the movement of the movable cutting member.
As explained earlier, the staple legs are cut by a movable cutting member which has received the staple legs after penetrating the material. The cutting member moves in the direction orthogonal to the penetrating direction of the staple legs while being guided by a guide portion of a fixed cutting edge. The first and second cutting edges cooperate to cut the staple legs just when the first cutting edges of the movable cutting member touch and pass by the second cutting edge of the fixed cutting member. Subsequently, movable clinchers are actuated, thereby obtaining a fine binding condition in which staple legs cut to an appropriate length are clinched.
In this way, the staple legs penetrating the material are cut separately from clinching, and the movable clinchers have no connection with the cutting effected on the staple legs. For this reason, the movable and fixed cutting members may assume their own configurations and adopt structures which are suitable only for cutting the staple legs. It is therefore possible to securely eliminate the above-mentioned unfavorable conditions in cutting and clinching.
More particularly, in the detailed embodiment two parts of cams have a given relative positional relation with respect to a drive shaft, one pair of cams engaging with one end of drive links each in turn having its central portion pivotally secured to a machine frame and the other end thereof connected to a holder for holding a staple driving member. The other pair of cams engage with cam links for driving a movable cutter for cutting the staple legs in association with a fixed wall member to cut the extra portions of the staple legs penetrating the material, the extra portions exceeding a predetermined length. A clincher link having its one end provided with a clincher press part is pivotally attached to the cam links, one end thereof being loosely fitted in the movable cutter. The movable clinchers for clinching the staple legs are axially supported on the fixed wall member, these movable clinchers being disposed above the clincher press part of the clincher link.
As discussed above, according to the present invention, upon actuation of the drive shaft, the two cams begin to rotate, and the holder causes the staple driving member to drive in the staple by dint of the rotation of one of the cams. As a result, the staple legs penetrate the material. The cam links are then operated by the other type of cams to actuate the movable cutter. If the staple legs passing through the material exceed the predetermined length, these extra portions are cut by the cutter in cooperation with the fixed cutter member. Subsequently, the cam links are operated, resulting in elimination of clearance caused by the loose fitting. Then the clincher link is operated together with the movable cutter, and the clincher press part is driven to rotate the movable clincher, thereby clinching the staple legs.
The cut-scraps of the staple legs in the stapler according to the present invention are disposed by a chute receiving cut legs and extending to an end and a closing member for closing the lower end opening by dint of gravity and pivotally secured to the lower end opening of the chute. Since the lower end opening is closed by the closing member, the cut-scraps are accumulated in the chute. However, the closing member can be easily pivoted to open the lower end opening, thus discharging the cut-scraps outside the chute in a simple manner.
As is obvious from the description given above, the present invention provides an excellent effect in practical use wherein the cut-scraps of the staple legs can simply be discharged and eliminated without requiring a special power source.